Astro Blog

By Daniel Clery , Science.  Excerpt: Staring deep into space and far back in time, a team of astronomers may have spotted a galaxy full of stars made from only the primordial gas created in the Big Bang. Such “population III stars” would have formed from hydrogen and helium and nothing else, and researchers have been searching for them for decades.... If confirmed, the discovery, made with NASA’s JWST space observatory, opens a window on the starting point of the chemical enrichment of the universe, in which the heavier elements needed to make planets and life began to be forged in stellar explosions. ...The nature of population III stars remains uncertain. Most theorists think they were huge, with masses up to 1000 times that of the Sun, 10 times larger than any star around today. ...The gigantic stars that resulted would also burn hot and fast, ending in a supernova explosion after just a few million years. That brief first flash of population III stars is hard for astronomers to...

By Robert Sanders , UC Berkeley News.  Excerpt: Mars today is a cold, dry, dusty planet with its only obvious water locked up in frozen polar ice caps. But billions of years ago, it appears to have had sandy beaches lapped by waves along the shoreline of a vast ocean. The evidence for beaches on Mars comes from a Chinese rover, called Zhurong, that landed on the planet in 2021. During its short life it detected evidence of underground beach deposits in an area thought to have once been the site of an ancient sea, bolstering the idea that the planet long ago had large bodies of water. ...between May 2021 and May 2022, Zhurong traveled 1.9 kilometers (1.2 miles) roughly perpendicular to escarpments thought to be an ancient shoreline from a time — 4 billion years ago — when Mars had a thicker atmosphere and a warmer climate. Along its path, the rover used ground penetrating radar (GPR) to probe up to 80 meters (260 feet) beneath the surface. ...“The structures don’t look like sand du...

By Sarah Stanley , Eos/AGU.  Excerpt: A closer look at previously disregarded observations reveals stronger evidence that a deep ocean lies beneath Callisto’s icy surface. ... Cochrane et al.  have revisited the Galileo data in more detail. Unlike in prior studies, this team incorporated all available magnetic measurements from Galileo’s eight close flybys of Callisto. Their expanded analysis much more strongly suggests that Callisto hosts a subsurface ocean....  Full article at https://eos.org/research-spotlights/jupiters-moon-callisto-is-very-likely-an-ocean-world . 

By Lan Dai  and  Axel Timmermann , ScienceAdvances.  Abstract summary: Asteroid Bennu has a 0.037% chance of colliding with Earth in 2182 CE.  The potential collision of such medium-sized asteroids would inject dust into the atmosphere and disrupting climate, vegetation, and marine productivity. Simulations show global temperature drop of 4°C, reduced precipitation, and significant decreases in terrestrial and marine net primary productivity....  Full article at https://www.science.org/doi/10.1126/sciadv.adq5399 .  See also Life’s Building Blocks Found in Bennu Samples (Eos/AGU)